The invention relates generally to methods of fabricating sensor array assemblies and, more particularly, to sensor array assemblies, where the sensor array is coupled to electronics.
Commonly used sensor arrays include light sensors, heat sensors, and acoustic sensors. An example of an acoustic sensor is an ultrasound transducer. Ultrasonic transducer assemblies are typically employed in applications including non-destructive evaluation (NDE) and medical diagnostic imaging, such as ultrasound applications. The ultrasonic transducer assembly generally includes an array of ultrasonic transducers coupled to an electronics array. The array may be one dimensional (1D) (a linear array or row of acoustic elements) for two-dimensional (2D) imaging. Similarly, the array may be a 2D array for volumetric imaging. The ultrasonic transducer array generally includes hundreds or thousands of individual transducers. Similarly, the electronics array includes hundreds or thousands of integrated interface circuits (or “cells”) which are electrically coupled to provide electrical control of the transducers for beam forming, signal amplification, control functions, signal processing, etc.
Piezoelectric transducers (PZT) are a widely used type of ultrasonic transducer. PZT sensors generally include a piezoelectric ceramic capable of changing physical dimensions when subjected to electrical or mechanical stress. Fabricating the transducer array and the electronics array, and coupling the two arrays together, provides a number of design challenges. Semiconductor based application specific integrated circuits (ASICs) are generally fabricated in wafer form and diced, providing a number of chips. PZT sensors are generally fabricated by dicing ceramic block material. Often PZT sensors are formed out of layers of ceramic, matching materials and damping materials. Each sensor sub-array typically includes many sensors. Each sensor sub-array or chip in the sensor array is typically coupled to an integrated circuit chip to provide individual control of each sensor. With hundreds or thousands of sensors and chips, each having countless electrical connections, the fabrication and assembly of such sensor assemblies can be challenging. This challenge becomes amplified when the application calls for size reduction in the sensor assembly.
Imaging transducers comprised of an acoustic array on an application specific integrated circuit are presently fabricated individually requiring a number of processing steps to be replicated for each manufactured transducer. This replication leads to a long manufacturing cycle and hence to a relatively high product cost. It would therefore be desirable to provide a process capable of manufacturing multiple electro-acoustic transducers at a time.